Tracking a Changing Climate
Wilson's Warbler: arriving later
In recent years, Wilson's Warblers have tended to arrive later than average.
Swainson's Thrush: no change
So far, there has been no detectable change in Swainson's Thrush arrival dates over time.
Orange-crowned Warbler: arriving earlier
In recent years, Orange-crowned Warblers have tended to arrive earlier than average.
Fox Sparrow: no change
So far, there has been no detectable change in Fox Sparrow arrival dates over time.
Golden-crowned Sparrow: arriving earlier
In recent years, Golden-crowned Sparrows have tended to arrive earlier than average.
Hermit Thrush: arriving earlier
In recent years, Hermit Thrushes have tended to arrive earlier than average.
Ruby-crowned Kinglet: arriving earlier
In recent years, Ruby-crowned Kinglets have tended to arrive earlier than average.
Point Blue staff and interns collect weather data several times each day at the Palomarin Field Station to understand how climate change (over the long-term) and weather fluctuations (over the short-term) affect birds. Weather plays a huge role in the daily lives of birds, from successfully raising young to surviving the winter, while climate change can affect the long-term stability of bird populations.
Record temperatures in 2017
To examine long-term weather patterns, we calculated annual average temperatures and total rainfall at Palomarin since 1976. Both measures have fluctuated over the last 40+ years, but temperatures have recently trended warmer. Through 2019, the most recent year of data included here, the hottest year we’ve recorded was in 2017. The wettest year we’ve recorded was in 1997-98 (during a strong El Niño). Recent years have been relatively dry, punctuated by a few wet winters.
Why is tracking weather and climate important for bird conservation?
Understanding how birds are affected by weather and climate requires long-term monitoring over decades. Because of our long-term bird monitoring and weather data collection at Palomarin, Point Blue has been able to identify changes in both the bird populations and the local climate, and uncover the links between them. This information helps us understand how well birds are adapting to climate change, and which species may be more vulnerable to climate change and may require more conservation attention. Here are just a couple examples of how our research has identified how birds are responding to global climate change.
Inconsistent Changes in Migration Timing
A changing climate may influence the seasonal timing (“phenology”) of blooming plants, hatching insects, and bird migration or nesting. In some cases, birds may not be able to easily change the timing of their migration to keep up with changes in the timing of their plant and insect food supplies, while others are shifting to try to stay in sync.
Spring arrivals. We have examined the dates migratory species arrive at Palomarin in the spring, and found that some species are arriving earlier (Orange-crowned Warbler), some are arriving later (Wilson’s Warbler), while others haven’t changed at all (Swainson’s Thrush).
The timing of bird arrivals in spring is thought to be adapted to the timing of food availability for successfully raising young, which may also be shifting with climate change. Earlier spring arrivals are consistent with warming trends and an earlier onset of spring. However, birds also need to be in good enough body condition to migrate, which might create delays in their arrivals at Palomarin.
Fall arrivals. Among species that arrive at Palomarin in the fall, Fox Sparrow hasn’t changed at all, while the others are arriving earlier. The timing of bird arrivals in fall likely reflect conditions to our north, with earlier fall arrivals suggesting an earlier end to their nesting season.
